by Ann Oldenburg, USA TODAY

by Ann Oldenburg, USA TODAY

Lee Thompson Young was handsome, successful and had his whole life ahead of him.

The Famous Jett Jackson star, who played Detective Barry Frost on TNT's Rizzoli & Isles, was discovered dead at his home with a self-inflicted gunshot wound to the head in Los Angeles Monday morning. He was 29.

And police are still trying to determine what happened.

"It's still a mystery. Evidently he was a clean-cut kid who didn't use alcohol and had no reported drug problem," a law enforcement source told the Daily News Tuesday.

The source said investigators recovered a gun at the scene but had not found a suicide note.

Described by those who knew him on the show as having a "positive energy" and "soulful grace," the Daily News says reports that Thompson had in recent years begun practicing Yoruba, an African-based religion, in a search for enlightenment.